The variation of the extinction coefficient of vitamin A with solvent

Abstract

The relative intensities of light absorption of a no. of purified vit. A concentrates have been detd. in the solvents ethyl alc., light petroleum, benzene and CHCl3. Taking the value for alc. as 1600 the other values average 1450, 1330 and 1330 respectively. When the values are detd. in the presence of the gross unsaponifiable matter of halibut liver oil the ratio 1600:1330 for alc.:CHCl3 remains unaltered. In the presence of the fatty components of the liver oils, however, the extinction coefficient in CHCl3 approaches that obtained for alc. solns. much more closely than in the case of the fat-free concentrates. The ratio appears to vary somewhat with different oils. The question of the spectrophoto-metric detn. of vit. A in butter and colostrum fats has been examined and discussed.